Recent years have witnessed practical use of a flat-panel display in various products and fields. This has led to a demand for a flat-panel display that is larger in size, that achieves higher image quality, and that consumes less power.
Under such circumstances, great attention has been drawn to an organic electroluminescent (hereinafter abbreviated to “EL”) display device that (i) includes an organic EL element which uses electroluminescence of an organic material and that (ii) is an all-solid-state flat-panel display which is excellent in, for example, low-voltage driving, high-speed response, and self-emitting.
An active matrix organic EL display device includes, for example, (i) a substrate made up of members such as a glass substrate and TFTs (thin film transistors) provided on the glass substrate and (ii) thin film organic EL elements provided on the substrate and electrically connected to the TFTs.
A full-color organic EL display device typically includes organic EL elements of red (R), green (G), and blue (B) as sub-pixels aligned on a substrate. A full-color organic EL display device carries out an image display by, with use of TFTs, selectively causing the organic EL elements to each emit light with a desired luminance.
Thus, such an organic EL display device needs to be produced through at least a process that forms, for each organic EL element, a luminescent layer having a predetermined pattern and made of an organic luminescent material which emits light of one of the above three colors.
The luminescent layer having a pattern can be formed by, for example, a vacuum vapor deposition method. In the vacuum vapor deposition method, vapor deposition particles are vapor-deposited onto a film formation target substrate through a vapor deposition mask (also referred to as a shadow mask) having openings in a predetermined pattern. In this case, the vapor deposition is carried out for each color of the luminescent layers (This is referred to as “selective vapor deposition”).
In so doing, a process for mass production is carried out by commonly using a method of carrying out vapor deposition while a film formation target substrate and a vapor deposition mask equivalent in size to the film formation target substrate are brought into close contact with each other. This method, however, requires the vapor deposition mask to be larger in size as the film formation target substrate is larger in size.
Such an increase in size of the vapor deposition mask easily causes a gap between the film formation target substrate and the vapor deposition mask due to self-weight bending and extension of the vapor deposition mask. Therefore, with a large-sized film formation target substrate in use, it is difficult to carry out patterning with high accuracy, and there will occur positional displacement of vapor deposition and/or color mixture. This makes it difficult to form a high-definition vapor-deposition pattern.
Further, as the film formation target substrate is larger in size, the vapor deposition mask, a frame that holds the vapor deposition mask, and others are enormously larger in size and weight. Thus, the increase in size of the film formation target substrate makes it difficult to handle, for example, the vapor deposition mask and the frame. This may cause a problem with productivity and/or safety. Further, a vapor deposition device itself and its accompanying devices are also larger in size and complicated. This makes device design difficult and increases installation cost.
In contrast, there is a scanning vapor-deposition method of, while scanning a film formation target substrate and a vapor deposition mask in a state in which they are spaced away from each other, carrying out vapor deposition on an entire surface of the film formation target substrate. The vapor deposition mask used in this method is smaller in size than the film formation target substrate. Thus, the scanning vapor-deposition method eliminates the problem characteristic of the use of a large-sized vapor deposition mask.
The scanning vapor-deposition method involves a vapor deposition source having a plurality of injection holes so arranged at a predetermined pitch in a direction perpendicular to the scanning direction as to allow vapor deposition particles to be injected.
In recent years, there have thus been proposed methods of limiting flows of vapor deposition particles (vapor deposition flows) with use of limiting plates so that vapor deposition particles injected from a first injection hole corresponding to a first region on a film formation target surface of a film formation target substrate will not fly toward a second region (hereinafter referred to as “adjacent film formation target region”) adjacent to the first region and corresponding to a second injection hole (adjacent nozzle).
Patent Literature 1 discloses, for example, that a blocking wall assembly is provided on one side of a vapor deposition source, the blocking wall assembly including, as limiting plates, a plurality of blocking walls partitioning a space between the vapor deposition source and a vapor deposition mask into a plurality of vapor deposition spaces. According to Patent Literature 1, since the blocking walls limit a vapor deposition range, it is possible to vapor-deposit a pattern with high definition while preventing spread of a vapor deposition pattern.